Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA.
Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA.
Nat Commun. 2017 Jul 19;8:15897. doi: 10.1038/ncomms15897.
A fundamental question in the study of chemical reactions is how reactions proceed at a collision energy close to absolute zero. This question is no longer hypothetical: quantum degenerate gases of atoms and molecules can now be created at temperatures lower than a few tens of nanokelvin. Here we consider the benchmark ultracold reaction between, the most-celebrated ultracold molecule, KRb and K. We map out an accurate ab initio ground-state potential energy surface of the KRb complex in full dimensionality and report numerically-exact quantum-mechanical reaction dynamics. The distribution of rotationally resolved rates is shown to be Poissonian. An analysis of the hyperspherical adiabatic potential curves explains this statistical character revealing a chaotic distribution for the short-range collision complex that plays a key role in governing the reaction outcome.
化学反应研究中的一个基本问题是，在接近绝对零度的碰撞能下，反应是如何进行的。这个问题不再是假设性的：现在可以在低于几十毫开尔文的温度下制造出原子和分子的量子简并气体。在这里，我们考虑了最著名的超冷分子 KRb 和 K 之间的基准超冷反应。我们在全维空间中绘制出 KRb 复合物的精确从头算基态势能表面，并报告数值精确的量子力学反应动力学。旋转分辨速率的分布被证明是泊松分布。对超球绝热势能曲线的分析解释了这种统计特征，揭示了在控制反应结果中起着关键作用的短程碰撞复合物的混沌分布。
